Rate of re-entrainment of circadian rhythms to advances of light-dark cycles may depend on ways of shifting the cycles.
When an 8-h advance of a light-dark (LD) cycle was accomplished by shortening of one dark period by 8 h, the rat pineal N-acetyltransferase rhythm was abolished during the first 3 subsequent cycles and reappeared in its original waveform during the fifth cycle only. When the 8-h advance shift was accomplished by lengthening of two consecutive light periods by 8 h, the N-acetyltransferase rhythm persisted and attained its original waveform by 2 days earlier than under the former shift. Re-entrainment is thus more rapid when the advance shift is accomplished by twice delaying than by once advancing of the LD cycle by 8 h.
Humlová
M
M
Institute of Physiology, Czechoslovak Academy of Sciences, Prague.
Illnerová
H
H
D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism*; D002940:Circadian Rhythm; D003213:Conditioning, Psychological; D003624:Darkness; D008027:Light; D008297:Male; D010870:Pineal Gland / Q000201:enzymology / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D001191:Arylamine N-Acetyltransferase